The present invention relates to a process and device for fighting a fire in an airplane compartment.
The invention relates not only to civil aviation for the transport of passengers, but also to aviation for the transportation of freight, as well as military aviation. It relates to the protection, from fire, of compartments adapted to receive baggage or material, such as airplane compartments, or else electronic bays, which contain the electrical interfaces of the airplane.
When a fire breaks out in such a compartment, in flight, it is necessary to contain it rapidly, so that the airplane can proceed to its destination, without the physical integrity of the passengers and of the equipment being endangered.
To this end, it is known to provide the compartment which it is desired to protect, with detectors adapted to detect, either the smoke from the fire, or the temperature increase connected to combustion. In the case of fire, these detectors generate an alarm signal, which is transmitted to the pilot. The latter then initiates the operation of a fire extinguisher which comprises, in the known state of the art, several cylinders containing an extinguishing agent under pressure, sold under the name xe2x80x9cHalon 1301xe2x80x9d.
When the pilot activates the extinguishing device, the extinguishing agent is vaporized in the compartment, by means of distribution lines, ending in nozzles opening into the mentioned compartment. It is a matter then of obtaining a concentration of the extinguishing agent in the air of the compartment, which will be comprised between 3 and 5%.
Then, during the rest of the flight, a continuous flow, at a lower rate, of extinguishing agent is continuously admitted into the compartment. Such a measure permits compensating any possible loss connected with the existing escape into the airplane.
This known solution however has certain drawbacks.
Thus, although the extinguishing agent used has a good capability of protecting against fire, and has only a low toxic risk, because it is used at low concentrations, it endangers the stratosphere of ozone layer.
Moreover, the duration of protection of the compartment depends directly on the volume of extinguishing agent employed. It is therefore not possible to ensure, in this way, a sufficient degree of safety for flights of very long duration, requiring long rerouting times, for example of eight hours. This would thus involve the taking onboard of a considerable volume of extinguishing agent, which would be unacceptable because of its weight and its size.
So as to overcome these various drawbacks, the invention proposes practicing a process which, whilst ensuring reliable control of a fire, over a long period of time, will not be detectably dangerous to the environment, in particular as to the destruction of the ozone layer and the greenhouse effect.
To this end, it has for its object a process for fighting fire in an airplane compartment, comprising a phase of detecting the presence of the fire, and a phase of extinguishing this fire, characterized in that the extinguishing phase comprises a phase of projection, into the compartment, of an extinguishing fluid, as well as a phase of generating air enriched in inert gas, from a source of compressed air within the aircraft, and a phase of admission of at least one portion of this enriched air into the compartment.
The projection of the extinguishing fluid, which is preferably water-based, permits lowering immediately the temperature prevailing in the compartment affected by the fire. This projection thus guarantees an instantaneous action on the fire, which contributes to controlling it effectively.
Moreover, the admission of air enriched in inert gas, principally in nitrogen, and hence impoverished in oxygen, ensures the maintenance of a low concentration of oxygen in the compartment, which is sufficiently low to prevent fire, once controlled by the projection of the extinguishing fluid, from propagating into the rest of the compartment.
Given that air enriched in inert gas is produced continuously from compressed air within the airplane, this enriched air is available for a time equal to that of the flight, such that rendering the compartment inert can be ensured during as long a light as is desired. The process of the invention thus provides a substantial advantage relative to the prior art, in which the onboard extinguishing agent is available only in a predetermined quantity.
Moreover, the process of the invention requires substantially no maintenance, contrary to the storage system of the prior art requiring frequent verification, or else periodic refilling.
The extinguishing device of the invention has a reduced weight and size, such that it does not substantially decrease the available volume for baggage that may be stored in the compartment.
To this end, it should be noted that, although it is envisagable to fight the fire solely by means of a liquid, such as water, such a solution would be unacceptable, given that it would have to use a considerable volume of this liquid.
Finally, the invention permits use of extinguishing and inerting agents which have substantially no impact on the environment, in particular on the ozone layer and the greenhouse effect.
According to other characteristics of the invention:
the air enriched in inert gas has an inert gas content comprised between 84 and 95%, preferably between 88 and 91%;
the extinguishing fluid is a liquid which is projected in atomized form into the compartment, by means of a gas under pressure;
the liquid contains water and the inert gas is comprised essentially of nitrogen.
The invention also has for its object an installation for fighting a fire in an airplane compartment, comprising means for detecting the presence of the fire, the means for extinguishing this fire, in which the extinguishing means comprise means for projecting, within said compartment, an extinguishing fluid, means for generating air enriched in inert gas, from a source of compressed air carried by the airplane, and means for admitting at least a portion of this enriched air to the interior of the compartment.
The invention also has for its object an aircraft provided with such an installation.